Tropical Storm Gustav has regained near hurricane strength this morning and may poses a threat to the US and Mexico next week. There is a lot of uncertainty and always a chance the storm will fizzle out or move away from populated areas. But an educated guess based on current data suggests something like a 50/50 chance that Gustav could make landfall early next week as a hurricane somewhere on the US Gulf Coast.

The image right shows the Tropical Cyclone Heat Potential (TCHP) for the Gulf of Mexico on August 24, 2008. The TCHP is a measure of storm producing and storm intensifying heat potential contained in given volume of ocean (The units are Kilojoules per square centimeter, not degrees).

The arrows between the Yucatan and west end of Cuba that turn and flow past the tip of Florida represent the Loop Current. The Loop is a massive current of warm, deep water that acts like a turbo-charger on any atmopsheric heat engine that might pass nearby. And, sometimes, pieces of the current break off ... Jeff Masters takes it from there:

When a Loop Current Eddy breaks off in the Gulf of Mexico at the height of hurricane season, it can lead to a dangerous situation where a vast reservoir of energy is available to any hurricane that might cross over. This occurred in 2005, when a Loop Current Eddy separated in July, just before Hurricane Katrina passed over and "bombed" into a Category 5 hurricane. ... This year, we had another Loop Current Eddy break off in July. This eddy is now positioned due south of New Orleans (Figure 2), and this eddy has similar levels of heat energy to the 2005 eddy that powered Katrina and Rita. Should Gustav pass over or just to the left of this eddy, we can expect the storm to significantly intensify.

The Aug 2008 Loop Current and breakaway hotspots are just one piece in a puzzle that's looking more and more similar to the 2004 and 2005 record setting storm seasons. If you live in or near a risk area, make plans, stock up now, know exactly where nearby shelters are. Pay attention to NHC updates, know what routes you are going to take and, if possible, your end destination in the event you have to evacuate. Better yet, for those in especially high risk areas, consider celebrating an extended Labor Day weekend well inland with friends or family.